UNIVERSITY    OF    CALIFORNIA    PUBLICATIONS 

IN 

ZOOLOGY 

Vol.  11,  No.  15,  pp.  51 1-528,  pis.  25-26,  1  text  fig.  April  15,  1314 


BY 

HARRY  JAMES  SNOOK  AND  J.  A.  LONG 


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Vol.  7.    (Contributions  from  the  Museum  of  Vertebrate  Zoology.) 

1.  Two  New  Owls  from  Arizona,  with  Description  of  the  Juvenal  Plum- 

age of  Strix  occidentals  occidentalis  (Xantus),  by  Harry  S.  Swarth. 

Pp.  1-8.    May,  1910      10 

2.  Birds  and  Mammals  of  the  1909  Alexander  Alaska  Expedition,  by 

Harry  8.  Swarth.  Pp.  9-172;  plates  1-6;  3  text-figures.  January,  1911.    1.50 
S.  An  Apparent  Hybrid  in  the  Genus  Dendroica,  by  Walter  P.  Taylor. 

Pp.  173-177.    February,  1911  05 

4.  The  Linnet  of  the  Hawaiian  Islands:   a  Problem  in  Speciation,  by 

Joseph  Grinnell.    Pp.  179-195.    February,  1911  15 

5.  The  Modesto  Song  Sparrow,  by  Joseph  GrinnelL    Pp.  197-199.    Feb- 

ruary, 1911  08 

6.  Two  New  Species  of  Marmots  from  Northwestern  America,  by  H.  B. 

Swarth.    Pp.  201-204.    February,  1911  OS 

7.  Mammals  of  the  Alexander  Nevada  Expedition  of  1909,  by  Walter  P. 

Taylor.    Pp.  205-307.    June,  1911  1.00 

8.  Description  of  a  New  Spotted  Towhee  from  the  Great  Basin,  by  J. 

Grinnell.    Pp.  309-till.    August,  1911  05 

9.  Description  of  a  New  Hairy  Woodpecker  from  Southeastern  Alaska,  by 

H.  S.  Swarth.    Pp.  313-318.    October,  1911  05 

10.  Field  Notes  on  Amphibians,  Eeptiles  and  Birds  of  Northern  Humboldt 
County,  Nevada,  with  a  Discussion  of  Some  of  the  Faunal  Features 
of  the  Eegion,  by  Walter  P.  Taylor.  Pp.  319-436,  plates  7-12. 

February,  1912  1-00 

Index,  pp.  437-446. 

Vol.  8.      1.  The  Vertical  Distribution  of  Eucalanus  elongatus  in  the  San  Diego 

Eegion  during  1909,  by  Calvin  O.  Esterly.    Pp.  1-7.    May,  1911 10 

2.  New  and  Eare  Fishes  from  Southern  California,  by  Edwin  Chapin 

Starks  and  William  M.  Mann.    Pp.  9-19,  2  text-figures.    July,  1911.      .10 

3.  Classification  and  Vertical  Distribution  of  the  Chaetognatha  of  the  San 

Diego  Eegion,  Including  Eedescriptions  of  Some  Doubtful  Speciss  of 

the  Group,  by  Ellis  L.  Michael.  Pp.  21-186,  pis.  1-8.  December,  1911.    1.78 

4.  Dinoflagellata  of  the  San  Diego  Eegion,  IV.  The  Genus  Gonyaulax,  with 

Notes  on  Its  Skeletal  Morphology  and  a  Discussion  of  Its  Generic 
and  Srieoiac  Characters,  by  Charles  Atwood  Kofoid.  Pp.  187-286, 
9-17. 


UNIVERSITY    OF    CALIFORNIA    PUBLICATIONS 

IN 

ZOOLOGY 

Vol.  11,  No.  15,  pp.  511-528,  pis.  25-26,  1  text  fig.  April  15,  1914 


PARASYNAPTIC   STAGES   IN   THE   TESTIS 
OF  ANEIDES  LUGUBRIS  (HALLOWELL) 

BY 

HAEEY  JAMES  SNOOK  AND  J.  A.  LONG 


INTRODUCTION 

In  many  of  the  theories  proposed  to  account  for  the  segre- 
gation of  hereditary  factors  a  more  or  less  specific  association 
between  the  factors  and  the  chromatic  elements  of  the  cell  is 
assumed.  Any  judgment  as  to  the  tenability  of  such  theories 
ought  to  be  based,  at  least  in  part,  upon  the  behavior  of  the 
chromosomes  themselves,  the  phenomena  of  synapsis  being  par- 
ticularly significant  in  this  connection.  The  present  study  has 
been  undertaken  in  an  effort  to  obtain  as  much  evidence  as 
possible  about  the  actual  conditions  during  the  synaptic  period. 
Inquiries  into  the  spermatogenesis  of  amphibians  have  contrib- 
uted much  towards  a  solution  of  the  problem,  and  it  has  seemed 
worth  while  to  extend  the  observations  to  another  representative 
of  the  same  class.  An  attempt  has  been  made  to  answer  the 
following  questions :  Is  there  a  stage,  or  a  series  of  stages,  in 
spermatogenesis  during  which  two  or  more  chromosomes  unite, 
or  in  any  manner  become  very  closely  associated  ?  If  so,  in  what 
manner  and  to  what  extent  does  the  process  take  place,  and  what 
is  the  subsequent  fate  of  the  elements  which  have  been  joined 
together?  This  inquiry  is  limited  to  the  synaptic  period  and 
the  stages  which  precede  or  immediately  follow  it. 

The  urodele,  Aneides  (=Autodax)  lugubris  (Hallowell),  was 
chosen  as  the  subject  of  this  investigation  for  the  following 


•«  % : :» •-  .•:•>•    ;;,,.;>  •  * *•• 

512          University  of  California  Publications  in  Zoology     [VOL.  11 

reasons:  (1)  The  male  sex  cells  are  large;  (2)  the  animal  is 
fairly  common  in  this  vicinity  and  may  be  obtained  throughout 
the  entire  year;  and  (3)  the  seriation  of  stages  within  the  testes 
is  easily  followed  because  all  phases  are  frequently  found  in  a 
single  testis,  beginning  at  the  anterior  end  with  lobules  of  sper- 
matogonia  and  passing  posteriorly  to  a  region  occupied  by  mature 
spermatozoa.  Moreover,  the  cells  in  any  particular  lobule  appear 
to  have  reached  approximately  the  same  stage  in  differentiation. 

The  material  used  for  this  research  was  obtained  within  a 
radius  of  five  miles  from  Berkeley,  with  the  exception  of  a  few 
specimens  from  Twin  Peaks,  San  Francisco,  and  much  of  it  was 
secured  upon  the  campus  of  the  University  of  California.  The 
salamanders  may  readily  be  found  under  stones  and  logs  or  in 
crevices  of  the  rocks.  They  have  also  been  taken  in  burrows 
at  least  a  foot  below  the  surface  of  the  soil,  but  in  all  such  cases 
observed  the  burrow  opened  beneath  a  rock.  It  is  difficult  to 
find  them  during  the  dry  season,  as  they  seek  the  deeper,  moist 
levels.  According  to  the  investigations  of  Hitter  and  Miller 
(1899),  they  breed  in  June  and  July.  Although  no  specimens 
were  collected  during  June,  July,  and  September,  material  was 
obtained  during  every  other  month. 

A  number  of  fixing  fluids  and  staining  processes  were  tried 
with  varying  success.  Bouin's,  Zenker's,  and  Flemming's  fluids 
proved  most  valuable  and  were  extensively  employed.  Gilson's 
fluid  seemed  to  damage  the  cells  of  the  outer  cysts;  otherwise, 
some  very  good  late  prophases  were  obtained  by  its  use.  The 
testes  were  embedded  in  paraffin  and  sectioned  longitudinally 
in  order  to  show  the  seriation  to  the  best  advantage.  The  sections, 
cut  from  six  to  twelve  micra  in  thickness,  were  mounted  on  slides 
in  the  usual  way. 

With  Bouin's  and  Zenker's  fluids  three  stains  were  tried: 
iron-alum-haematoxylin  with  orange  G  and  acid  fuchsin  as  coun- 
terstains;  safranin  followed  by  gentian  violet;  and  phospho- 
tungstic  acid  haematoxylin.  The  last  seems  to  be  the  best  for 
general  purposes,  as  it  stains  the  growing  spermatocyte  beauti- 
fully without  overstaining  the  mitotic  figures.  It  differentiates 
the  structures  of  the  cell  very  clearly,  staining  the  chromosomes 
deep  blue  and  the  spindles  reddish.  Many  equatorial  plates  can 


19141        Snook-Long:  Parasynapsis  in  Aneides  lugubris          513 

be  excellently  demonstrated  with  safranin  and  gentian  violet 
after  Zenker's  or  Bouin's  solutions.  Material  fixed^jn  Flem- 
ming's  solution  was  stained  either  with  safranin  and  gentian 
violet  after  the  Gram  method,  or  with  iron-alum-haematoxylin 
and  orange  G.  Gilson's  fluid  was  followed  by  safranin  and 
lightgreen. 

A  few  testes,  fixed  in  Flemming  's  solution  and  passed  through 
the  alcohols  to  seventy  per  cent,  were  divided  into  four  or  five 
parts  which  were  transferred  with  a  drop  of  alcohol  to  slides 
prepared  with  egg  albumen  and  then  thoroughly  crushed  and 
ground  up  under  a  cover  glass.  The  seventy  per  cent  alcohol 
was  then  drawn  off  and  the  albumen  coagulated  by  dropping 
ninety  per  cent  alcohol  upon  it,  fixing  the  fragments  and  loose 
cells  to  the  glass.  The  material  thus  prepared  was  carried 
through  the  alcohols  and  stained  either  in  iron-alum-haema- 
toxylin without  counterstains,  or  in  safranin  with  gentian  violet. 
While  many  of  the  cells  were  broken  up,  or  flattened  out,  a 
considerable  number  remained  intact.  Because  of  their  large 
size  they  are  somewhat  opaque,  but  most  of  them  are  clear  enough 
for  study.  This  method  destroys  every  evidence  of  seriation  and 
for  that  reason  is  not  of  great  value  by  itself,  yet,  taken  in 
connection  with  the  sectioned  material,  it  has  been  found  very 
useful.  This  type  of  preparation,  in  which  the  structures  are 
entire,  was  most  largely  used  in  the  determination  of  the  number 
of  chromosomes  previous  to  the  first  maturation  division. 

THE  SPERMATOGONIA 

The  anterior  portion  of  the  testis  is  occupied  by  spermatogonia 
and  occasionally  lobules  may  be  seen  which  are  filled  entirely, 
or  in  part,  with  cells  in  the  process  of  division.  Among  these 
it  is  possible  to  pick  out  polar  views  of  the  equatorial  plate.  By 
first  carefully  drawing  them  with  the  aid  of  a  camera  lucida, 
and  then  counting  the  chromosomes  shown  in  the  resulting  sketch, 
the  number  and  form  were  determined.  It  was  not  always  pos- 
sible to  demonstrate  each  element  clearly,  owing  to  the  sinuous 
form  of  many  of  the  chromosomes  and  the  tendency  for  them 
to  gather  in  clumps,  more  or  less  masking  those  below;  and  in 


514          University  of  California  Publications  in  Zoology     [VOL.  11 

many  cases  it  could  only  be  discerned  that  there  were  more  than 
twenty-five  and  less  than  thirty.  Discarding  the  latter  as  doubt- 
ful, there  still  remained  nine  clear  cases  in  which  the  number 
was  definitely  twenty-eight,  and  one  case,  just  as  clear,  in  which 
it  was  only  twenty-three. 

Plate  25,  figure  1,  represents  this  latter  and  plate  25,  figure  2, 
illustrates  the  more  usual  condition.  They  are  drawn  from  cells 
in  one  section,  located  near  each  other  in  the  same  lobule.  The 
two  small  elements  in  the  center  of  the  plate  in  both  figures  are 
quite  characteristic  of  this  stage,  and,  although  they  cannot 
always  be  found  occupying  the  same  relative  position,  and  may 
sometimes  be  widely  separated,  they  can  usually  be  identified 
with  chromosomes  of  the  same  general  size  and  shape  lying  within 
the  ring  in  other  spindles.  The  chromosomes  appear  to  be  band- 
shaped  and  are  usually  bent  into  the  form  of  a  letter  U  with 
the  free  ends  pointing  outward.  There  is  considerable  variation 
in  size  and  shape  and  in  their  position  with  reference  to  the 
spindle. 

A  split  can  frequently  be  discerned  in  the  chromosomes  of 
the  equatorial  plate,  as  is  shown  by  several  elements  in  the  cells 
figured.  It  is  believed  that  this  is  evidence  that  the  plate  is 
fully  formed  and  that  division  is  about  to  occur.  Many  dividing 
cells  are  situated  in  the  immediate  vicinity  of  these  two. 

The  significance  of  the  lesser  number  shown  in  figure  1  is 
not  known,  nor  is  it  possible  to  say  just  how  widely  such  varia- 
tions occur.  In  the  case  under  consideration  there  is  no  evidence 
that  the  condition  is  in  any  sense  abnormal,  for  it  does  not  differ 
from  the  others  except  in  the  number  of  chromosomes.  This 
plate  lies  in  a  section  twelve  micra  thick,  and  the  following 
section  shows  only  a  few  tips  in  the  remainder  of  the  cell. 

Although  such  exceptional  cases  certainly  exist,  even  a  casual 
exploration  of  the  lobules  of  dividing  spermatogonia  will  con- 
vince one  that  in  a  large  majority  of  cases  more  chromosomes  are 
present  than  are  delineated  in  figure  1.  In  view  of  the  fact  that 
in  every  clear  case  found,  with  the  exception  noted,  twenty-eight 
definite  elements  could  be  made  out,  it  seems  justifiable  to  say 
that  the  number  of  chromosomes  in  the  equatorial  plate  of 
Aneides  is  usually,  but  not  universally,  twenty-eight. 


1914]        Snook-Long :  Parasynapsis  in  Aneides  lugubris          515 

THE  SPERMATOCYTE 

Following  the  last  spermatogonial  telophase,  the  chromatin 
becomes  very  diffuse  and  is  irregularly  distributed  in  the  form 
of  clumps  or  "net-knots"  connected  by  fine  threads  (pi.  25, 
fig.  3).  If  there  is  any  arrangement  or  order  in  these  threads, 
it  is  completely  masked  by  the  patches  of  chromatin,  nor  is  there 
any  suggestion  of  orderliness  in  the  size  or  distribution  of  the 
latter.  There  is  no  clear  evidence  of  a  "  chromoplast "  as  de- 
scribed by  Eisen  (1900)  and  later  by  Janssens  (1905)  in  the 
male  sex  cells  of  Batrachoseps  attenuatu». 

Janssens  also  found  evidence  of  a  rotation  of  the  nucleus 
during  this  period,  whereby  the  "chromoplast,"  at  first  in  the 
neighborhood  of  the  sphere,  came  to  lie  opposite  it.  In  Aneides 
the  sphere  is  found  at  one  side  of  the  nucleus,  but  further  than 
that  it  has  been  impossible  to  demonstrate  any  relation  between 
it  and  the  elements  of  the  nucleus  until  the  resting  stage  is  past. 

In  lobules  more  posterior  than  those  containing  the  resting 
nuclei  the  fine  threads  gradually  become  more  pronounced  and 
can  be  followed  without  difficulty  for  considerable  distances.  At 
the  same  time  it  is  plain  that  the  threads  are  of  greater  diam- 
eter and  stain  more  heavily  in  the  region  of  the  sphere  than 
in  the  rest  of  the  nucleus.  The  net-knots  appear  smaller  and 
are  comparatively  few,  especially  in  the  immediate  vicinity  of 
the  sphere,  which  may  be  said  to  lie  at  the  proximal  pole  of  the 
nucleus.  In  this  region  the  threads  appear  somewhat  con- 
densed (pi.  25,  fig.  4)  and  close  observation  shows  that  they  are 
associated  two  by  two  in  such  a  manner  that  when  viewed  from 
the  side  they  resemble  the  letter  V,  with  the  angle  pointing 
toward  the  sphere  and  the  diverging  arms  prolonged  in  the 
opposite  direction.  They  are  unbranched,  as  was  also  found  to 
be  true  for  Salamandra  by  the  Schreiners  (1906)  and  for  Batra- 
choseps by  Janssens  (1905),  the  description  of  the  conditions  in 
Batrachoseps  being  confirmed  by  Wilson  (1912),  who  examined 
Janssens'  preparations.  Sections  fixed  in  Bouin's,  Zenker's,  or 
Flemming's  solutions  and  stained  in  a  variety  of  ways  show  this 
peculiarity.  At  this  stage  the  distal  portion  of  the  nucleus  shows 
no  such  polar  orientation,  and  if  the  sections  should  be  so  cut 


516          University  of  California  Publications  in  Zoology     [VOL.  11 

as  to  include  this  part  only  it  could  be  distinguished  with 
extreme  difficulty,  if  at  all,  from  the  preceding  stage. 

Comparatively  few  of  the  cells  examined  exhibited  the  V- 
figures  when  observed  from  the  side,  the  greater  number  dis- 
playing a  Y-shaped  arrangement  of  the  threads  in  the  vicinity 
of  the  proximal  pole,  with  the  stem  of  the  Y  ending  in  the 
immediate  neighborhood  of  the  sphere  and  the  arms  drawn  out 
into  fine  threads  which  are  lost  in  the  distal  portion  of  the  nucleus 
(pi.  25,  fig.  5).  In  the  part  of  a  section  which  contains  sperma- 
tocytes  in  this  condition  there  is  a  gradual  change  from  the  V- 
to  the  Y-figure;  the  cells  characterized  by  the  short-stemmed 
Y-figures  give  place  gradually  to  those  in  which  a  long-stemmed 
figure  predominates  (pi.  25,  figs.  6  and  7)  ;  and  in  the  individual 
nuclei  there  is  considerable  variation  in  the  length  of  the  struc- 
ture from  the  free  end  to  the  fork.  At  times  the  thick  threads 
seem  also  to  be  double,  but  it  is  not  possible  to  demonstrate  this 
condition  in  most  cases.  As  the  length  of  the  stems  of  the  Ys 
increases  the  extent  of  the  network  diminishes. 

As  can  be  easily  imagined,  it  is  practically  impossible  to 
determine  with  accuracy  in  this  stage  the  number  of  the  V-  and 
Y-figures,  and  of  the  fine  threads  of  which  they  are  composed. 
While  the  threads  are  perfectly  clear  in  side  views,  they  are 
easily  confused  when  seen  from  one  end.  Nevertheless,  in  one 
nucleus  corresponding  to  figure  4,  so  cut  that  the  part  containing 
the  pairing  threads  was  viewed  from  the  pole,  a  diagram  indi- 
cated the  presence  of  twenty-six  to  thirty  Vs  and  Ys,  or,  in  other 
words,  of  fifty-two  to  sixty  threads;  and  in  another  case  in  a 
stage  like  that  shown  in  figure  6  there  were  clearly  twenty-eight 
thick  threads  (stems  of  Ys). 

This  stage  corresponds  closely  to  that  figured  by  Janssens 
(1905)  in  his  paper  on  the  spermatogenesis  of  Batrachoseps  and 
designated  by  him  the  amphitene,  in  distinction  to  the  preceding 
or  leptotene  condition  in  which  the  fine  threads  are  not  united. 
Much  stress  is  placed  upon  it  by  the  Schreiners  (1906)  in  their 
discussion  of  the  spermatogenesis  of  Salamandra  maculosa  as 
the  stage  in  which  a  conjugation  of  the  chromosomes  takes  place. 
Many  writers  have  overlooked  it  entirely,  because,  no  doubt,  of 
its  close  resemblance  to  the  leptotene  period  and  the  small  number 


1914]        Snook-Long:  Parasynapsis  in  Aneides  lugubris          517 

of  nuclei  usually  found  in  this  condition.  If  the  number  of 
amphitene  cells  can  be  taken  as  an  indication  of  the  tturation  of 
the  period,  it  must  be  considered  as  relatively  short,  because  the 
cells  occupy  a  much  smaller  proportion  of  the  testis  than  either 
the  spermatogonia  or  the  cells  that  have  advanced  to  the  next 
stage. 

Posterior  to  the  region  in  the  testis  last  described  are  nuclei 
containing  horseshoe-shaped  loops,  with  their  free  ends  turned 
towards  the  sphere  and  their  bends  in  the  distal  half.  They  appear 
somewhat  granular  (pi.  25,  fig.  8  and  pi.  26,  fig.  10).  These  loops 
have  been  described  in  a  number  of  urodeles  and  would  appear 
to  be  very  characteristic  of  spermatogenesis  in  salamanders.  In 
thickness  they  exceed  somewhat  the  thick  threads  formed  by  the 
union  of  two  fine  diverging  ones.  No  trace  of  the  latter  can  now 
be  seen.  Cross-sections  through  the  proximal  portion  of  the 
nucleus  show  clearly  twenty-eight  cut  ends,  demonstrating  the 
number  of  loops  to  be  fourteen  (pi.  26,  fig.  11).  Polar  views 
show  the  presence  of  twenty-eight  converging  threads  with  their 
free  ends  crowded  together  in  the  immediate  vicinity  of  the 
sphere  and  very  near  to  the  nuclear  membrane  (pi.  26,  fig.  9). 

It  will  be  remembered  that  this  polar  orientation  is  also  a 
characteristic  of  the  preceding  stage,  a  lateral  view  showing  the 
same  arrangement  of  the  thick  threads  forming  the  stem  of  the 
Y-figure  as  is  here  presented  by  the  ends  of  the  loops.  This 
resemblance  is  very  marked,  indeed,  and  together  with  the  evi- 
dence afforded  by  seriation  leads  to  the  conclusion  that  the  loop 
is  derived  from  two  fine  threads  wrhich  have  now  completely 
disappeared  as  separate  threads  and  have  fused  into  one. 

Up  to  this  point  the  cells  have  been  gradually  increasing  in 
volume,  a  fact  which  makes  seriation  more  certain;  but  during 
the  stage  of  well-developed  loops  relatively  little  growth  takes 
place.  As  the  cells  in  this  condition  usually  occupy  a  rather 
large  portion  of  the  testis,  it  seems  probable  that  this  period  lasts 
for  a  much  longer  time  than  the  amphitene  stage. 

Later  all  evidences  of  polarization  are  lost  and  the  chromo- 
somes end  without  apparent  relation  to  the  position  of  the  centro- 
somes  or  to  each  other.  At  the  same  time  a  longitudinal  split 
develops,  dividing  each  loop  more  or  less  completely  into  two 


518          University  of  California  Publications  in  Zoology     tv°L-  n 

portions  throughout  the  greater  part  of  its  length,  but  leaving 
one  or  both  of  the  ends  intact  (pi.  26,  fig.  12),  a  process  which 
is  the  reverse  of  the  one  previously  described.  Cells  in  which 
the  split  is  developing  can  readily  be  distinguished  from  those 
in  the  amphitene  stage,  by  the  absence  of  polarization,  by  their 
larger  size,  and  by  their  position  in  the  testes  near  the  region  -in 
which  the  maturation  divisions  take  place.  They  are  separated 
from  the  amphitene  cells  by  the  extensive  and  clearly  defined 
region  of  the  polarized  loops. 

This  and  the  subsequent  stages  in  amphibians  have  been 
described  so  frequently  since  first  pointed  out  by  Fleming  (1887) 
that  they  need  not  be  discussed  in  detail  here.  According  to 
Hermann  (1889),  Meves  (1897),  Eisen  (1902),  Janssens  (1901, 
1905),  Kingsbury  (1902),  and  other  careful  investigators,  the 
longitudinal  halves  of  the  loop  are  separated  in  the  first  matura- 
tion division.  This  seems  to  be  true  in  the  case  of  Aneidcs.  The 
split  loops  shorten,  thicken,  and  at  the  same  time  become  twisted 
to  form  what  Janssens  designates  the  streptotene  stage  (pi.  26, 
fig.  13).  They  finally  form  heterotypical  chromosomes,  the  halves 
of  which,  corresponding  to  the  halves  of  the  split  loops,  pass  to 
opposite  poles  during  the  following  anaphase. 

A  number  of  spindles  representing  the  first  maturation  div- 
ision were  examined  and  some  drawn  with  the  aid  of  the  camera 
lucida  (pi.  26,  fig.  14).  The  number  of  chromosomes  was  four- 
teen, though  fifteen  were  counted  in  two  cases.  In  the  latter, 
however,  from  the  position  of  the  chromosomes  it  seems  probable 
that  a  chromosome  had  just  divided  and  it  is  possible  that  four- 
teen was  the  original  number  in  all  cases  examined.  Both  sections 
and  entire  cells  were  employed  in  making  these  counts,  the  latter 
being  found  particularly  valuable.  While  they  are  frequently 
somewhat  dense  and  often  pressed  out  of  shape,  it  is  hardly 
possible  that  any  of  the  chromosomes  could  be  lost  without  rup- 
turing the  cell  membrane.  In  that  case  the  loss  would  be  detected. 

DISCUSSION  AND  CONCLUSIONS 

As  previously  mentioned,  the  usual  number  of  chromosomes 
found  in  the  equatorial  plate  of  the  spermatogonial  spindle  is 


1914]        Snook-Long:  Parasynapsis  in  Aneides  lugubris          519 

twenty-eight.  In  the  stage  of  the  polarized  loops,  cross-sections 
and  polar  views  in  the  neighborhood  of  the  sphere  jiidicate  the 
number  of  loops  to  be  fourteen,  which  agrees  with  the  number  of 
chromosomes  comprising  the  equatorial  plate  of  the  first  matura- 
tion division.  This  difference  between  twenty-eight  and  four- 
teen is  to  be  expected  if  the  chromosomes  conjugate  whether  by 
the  parasynaptic  or  telosynaptic  method. 

Meves  (1911)  avoids  the  problem  of  synapsis  by  stating :  "Die 
Geschlechtszellen  bezw.  ihre  Kerne  haben  nach  meiner  Vorstel- 
lung  (1907)  die  besondere  Eigenschaft  ererbt,  beim  Eintritt  in 
die  Wachstumsperiode  nur  die  halbe  Zahl  von  Chromosomen 
auszubilden. "  To  which  Wilson  (1912)  replies,  "Certainly  the 
adoption  of  this  simple  solution  would  save  a  great  deal  of 
trouble;  but  I  fear  that  the  facts  compel  us  to  take  a  more 
roundabout  way  out  of  our  difficulties."  A  condition  so  well- 
defined  and  clear  as  the  amphitene  stage  would  seem  to  be  too 
significant  to  be  thus  lightly  considered. 

This  has  been  interpreted  by  different  investigators  to  repre- 
sent either  a  union  of  two  threads  (the  Schreiners  (1906), 
Janssens  (1905,  1908),  Wilson  (1911),  or  a  splitting  of  one 
Meves  (1908),  Goldschmidt  (1908),  Fick  (1908).  In  Aneides 
the  evidence  afforded  by  seriation  as  recapitulated  below  seems  to 
the  writers  to  point  toward  the  former  interpretation. 

1.  Fine,  unpaired  threads  become  polarized  with  respect  to 
that  side  of  the  nucleus  near  which  lies  the  sphere,  the  proximal 
pole. 

2.  Coincident  with  this  polarization,  threads  are  found  asso- 
ciated two  by  twro  at  the  proximal  pole  of  the  nucleus. 

3.  By  the  association  of  any  two  threads  there  is  formed  a 
figure,  which,  when  observed  from  a  position  at  right  angles  to 
an  axis  passing  through  the  poles  of  the  cell,  resembles  the  letter 
V  with  the  angle  turned  toward  the  sphere. 

4.  Seriation  showys  that  the  V-shaped  figures  are  succeeded  by 
Y-like  figures,  of  which  the  stem,  frequently  exhibiting  a  double 
condition,  lies  in  the  region  of  the  centrosomes,  while  the  arms 
diverge  widely  away  from  the  sphere.     Furthermore,  it  may  be 
observed  that  as  this  stage  becomes  more  advanced,  the  stem  of 
the  Y  increases  in  length  at  the  expense  of  the  arms. 


520          University  of  California  Publications  in  Zoology     [VOL.  11 

5.  More  posterior  in  the  testes  the  Y-figures  are  replaced  by 
loops  showing  the  same  polarization,  i.e.,   with  the   free   ends 
directed  toward  the  sphere  while  the  bends  are  found  in  the 
region  opposite  to  the  centrosomes. 

6.  At  this  stage  the  fine  threads  can  no  longer  be  detected  and 
the  loops  appear  as  single  threads. 

This  evidence  leads  to  the  conclusion  that  the  loops  are  formed 
by  the  union  of  the  fine  threads.  A  more  critical  examination 
of  the  early  stages  raises  the  question  as  to  what  are  the  relations 
of  the  conjugating  leptotene  threads  to  each  other.  Up  to  this 
point  the  individual  V-  or  Y-figures  described  in  any  one  nucleus 
have  been  considered  as  unrelated  to  each  other.  If  there  are 
only  fourteen  bifid  figures  in  any  one  nucleus,  each  must  be 
considered  one  end  of  a  loop  in  the  later  polarized  stage,  the 
other  end  of  the  loop  not  yet  having  come  into  existence.  But 
since  there  are  about  twenty-eight  pairs  of  threads  at  the  begin- 
ning of  polarization  and  since  the  twenty-eight  free  ends  of  the 
completed  loops-  directed  toward  the  proximal  pole  correspond 
in  position  to  the  stems  of  the  Ys,  it  leads  one  to  think  that  the 
two  ends  of  each  loop  are  formed  simultaneously  and  before  the 
middle  part  comes  into  existence. 

While  the  foregoing  is  strong  evidence  that  the  stem  of  each 
Y-figure  becomes  one  end  of  a  polarized  loop,  the  way  in  which 
the  two  ends  of  each  loop  become  associated  remains  to  be  con- 
sidered. It  will  be  remembered  that  each  one  of  the  fifty-six 
short,  fine,  leptotene  threads  which  unite  in  one  way  or  another 
to  form  the  fourteen  loops  is  indirectly  continuous  with  the  others 
through  the  medium  of  the  network.  The  further  evolution  of 
these  threads  might  be  thought  of  in  one  of  two  ways.  In  the 
first  place  the  fifty-six  threads  might  be  imagined  as  separate, 
individual  filaments  which  pair  to  form  the  twenty-eight  Y- 
figures;  in  the  second  place,  they  may  be  conceived  of  as  not  so 
many  independent  parts,  but  as  so  definitely  related  that  each 
branch  of  each  Y  would  be  one  end  of  a  potential  thread,  the 
•other  end  of  which  would  be  represented  by  one  of  the  branches 
of  some  other  Y. 

In  regard  to  the  first  of  these  possibilities,  it  might  be  argued 
that  the  arms  of  the  Y-figures  on  one  side  meet  and  join  with 


1914]        Snook-Long :  Parasynapsis  in  Aneides  lugubris          521 

similar  arms  of  Y's  on  the  other  side,  giving  rise  to  the  loop  by 
a  process  of  telosynapsis  in  addition  to  parasynapsjs^  jjfig.  A). 
That  there  is  no  evidence  for  such  a  conclusion  is  indicated  by 
the  observation  that  threads  may  frequently  be  followed  for  long 
distances  around  the  nucleus  and  that  free  ends  have  never  been 
found  except  in  the  vicinity  of  the  sphere.  When  the  threads 
are  definitely  formed,  there  are  no  morphological  indications  that 
an  end-to-end  union  has  taken  place. 

These  considerations  indicate  at  once  the  validity  of  the 
second  alternative,  for  if  the  threads  exhibit  no  free  ends  except 
at  the  proximal  pole  of  the  nucleus  where  they  unite  to  form  the 
Y-figures,  it  seems  reasonable  to  conclude  that  they  represent 
the  ends  of  twenty-eight  threads  which  are  evolved  from  their 
ends  towards  their  middle  at  the  expense  of  the  nuclear  netwrork. 
In  other  words,  each  of  the  fifty-six  threads  becomes  directly 
continuous  with  one  only  of  its  own  kind  by  the  time  that  the 
loops  are  complete.  If  this  conception  of  their  origin  and  nature 
be  sound,  the  way  in  which  they  become  associated  in  the  loops 
might  be  interpreted  in  one  of  two  ways:  (1)  The  loops  may 
be  formed  by  the  association  of  two  potential  threads  by  a 
process  which  begins  at  approximately  the  same  time  at  both 
ends  (fig.  J3).  (2)  One  leptotene  thread  might  be  joined  at  the 
ends  to  two  other  threads  (fig.  C).  Both  of  these  interpretations 
have  one  feature  in  common,  that  of  a  side-to-side  union.  There 
seems,  however,  to  be  little  reason  to  believe  that  the  second 
condition  actually  exists  in  the  male  sex  cells  of  Aneides.  If 
each  leptotene  thread  were  joined  at  the  ends  to  other  threads 
at  the  beginning  of  polarization  (fig.  C),  as  the  bifid  figures 
closed  up,  most  of  the  threads  would  be  drawn  together  in  one 
or  more  points  in  the  region  of  the  distal  pole  of  the  nucleus 
(fig.  D),  which  is,  in  fact,  the  region  of  widest  separation.  The 
fact  that  there  is  no  evidence  of  such  behavior  upon  the  part  of 
the  threads  would  seem  to  dispose  of  this  interpretation. 

Therefore,  it  seems  probable  that  the  number  of  pairing 
threads  is  twenty-eight  and  that,  as  rapidly  as  they  are  evolved, 
they  unite  two  by  two,  side  by  side,  and  at  both  ends,  the  middle 
part  of  the  potential  threads  being  lost  in  the  distal  half  of  the 
nucleus. 


522          University  of  California  Publications  in  Zoology     [VOL.  11 


B 


G  D 

Figs.  A  to  D. — Diagrams  to  illustrate  possible  modes  of  association  in 
synapsis  of  the  fifty-six  fine  threads  (leptotene)  which  are  formed  from 
the  nuclear  network  and  become  polarized  with  regard  to  the  sphere  which 
lies  at  the  proximal  side  of  the  nucleus.  The  large  outer  circle  represents 
the  cell  wall;  the  large  inner,  the  nuclear  membrane;  the  small  one  between 
the  two  large,  the  sphere. 

Fig.  A. — Of  the  fifty-six  threads  which  are  imagined  as  separate,  dis- 
tinct filaments  eight  are  represented  as  forming  two  loops  (amphitene) 
by  a  double  process  of  pairing.  They  form  by  parallel  union  four  (of  the 
twenty-eight)  Ys  which  by  end  to  end  junction  give  rise  to  the  loops. 
There  is  no  evidence  of  such  a  condition. 

Fig.  B. — Four  complete  threads  are  indicated,  the  eight  ends  of  which, 
corresponding  to  the  eight  separate  threads  of  figure  A,  arise  separately, 
are  at  first  merged  into  the  nuclear  network  of  the  distal  part  of  the 
nucleus,  and  with  the  disappearance  of  the  network  become  continuous 
as  four  threads.  These  before  completion  and  whi-le  potentially  present 
in  the  network  become  paired  in  such  a  manner  that  the  ends  of  two 
threads  unite  to  form  two  Ys,  which  by  closing  up  give  rise  to  a  single 
loop  which  is  unconnected  with  the  other.  Fourteen  such  loops  are  formed. 

Fig.  C. — The  complete  threads  arise  as  in  figure  B.  A  different  mode 
of  synapsis  is  represented  in  which  the  two  ends  of  one  complete  thread 
are  not  paired  with  the  two  ends  of  only  one  other  thread,  but  with  one 
end  each  of  two  other  threads. 

Fig.  D. — A  later  stage  of  the  condition  shown  in  figure  C,  showing 
how  with  the  final  closing  of  the  Ys  the  bends  of  the  loops  would  be  drawn 
together,  a  condition  not  existing. 


1914]        Snook-Long:  Parasynapsis  in  Aneides  lugubris          523 

With  these  facts  and  considerations  in  mind,  it  is  concluded 
that  the  V-  and  Y-figures  do  not  indicate  a  splitting,  _as  main- 
tained by  some,  but  that  they  represent  a  progressive,  parallel 
union  or  conjugation  of  fine  (leptotene)  threads;  in  other  words, 
a  parasynaptic  union.  This  union  takes  place  during  the  amphi- 
tene  stage  and  leads  to  the  formation  of  the  single,  thick,  polarized 
loops.  There  is  no  reason  for  confusing  the  split  which  does  occur 
in  the  stage  following  the  formation  of  the  loops  (and  wrhich  may 
be  the  reverse  of  parasynapsis)  with  the  union  in  the  amphitene 
stage,  since  the  two  stages  are  easily  distinguishable  both  by  their 
appearance  and  position  in  the  testis. 

The  evidence  set  forth  above  does  not  warrant  an  assertion 
that  the  conjugating  leptotene  threads  are  identical  with  the 
spermatogonial  chromosomes.  Nevertheless,  the  fact  that  the 
number  of  chromosomes  (tetrads)  in  the  first  maturation  spindle 
is  half  that  of  the  chromosomes  in  the  spermatogonial  division, 
together  writh  the  evidence  that  the  tetrads  are  formed  by  the 
union  of  threads  evolved  from  the  nuclear  network  which  in 
turn  is  formed  from  the  chromosomes  of  the  last  spermatogonial 
telophase,  suggests  very  strongly  that  the  spermatogonial  chro- 
mosomes which  went  into  the  nuclear  network  reappear  as  the 
pairing  leptotene  threads.  This  idea  is  further  supported  by  the 
manner  in  which  the  two  branches  of  two  Ys  become  continuous 
as  though  they  were  the  ends  of  threads  (chromosomes)  poten- 
tially existing  in  the  network,  though  not  distinguishable  as  such. 
Or,  to  reverse  the  conception,  if  it  is  considered  that  the  sperma- 
togonial chromosomes  retain  their  continuity  throughout  the 
resting  stage  of  the  nucleus,  then  it  is  easier  to  comprehend  why 
the  proper  'Y-figures  become  associated  as  the  leptotene  threads 
are  evolved,  for  the  chromosomes,  though  in  modified  form  and 
only  partly  distinguishable  as  threads,  begin  to  pair  as  they 
might  if  pairing  were  delayed  until  they  were  completely  formed. 
Although  this  way  of  stating  the  conception  is  open  to  the  criti- 
cism that  it  is  an  argument  in  a  circle,  still  the  conception  is 
worthy  of  consideration  as  having  some  weight  on  the  positive 
side  of  the  question  of  the  individuality  of  the  chromosomes. 

It  has  already  been  pointed  out  that  the  stage  of  the  polarized 
loops  which  follows  that  of  the  conjugation  of  the  leptotene 


524         University  of  California  Publications  in  Zoology     [VOL.  11 

threads  has  a  relatively  much  longer  duration  than  any  other  of 
the  stages  of  the  prophase  of  the  first  maturation  division.  If 
it  is  true  that  the  conjugating  threads  have  the  value  of  paired 
maternal  and  paternal  chromosomes  and  constitute  the  mechan- 
ism for  the  segregation  and  recombination  of  mendelian  char- 
acters or  their  factors,  it  is  to  be  noted  that  there  is  ample 
opportunity  for  the  reconstitution  of  the  chromosomes  and  for 
any  interchange  of  substances  composing  the  chromosomes  which 
may  be  concerned  in  the  transmission  of  inherited  characters. 

SUMMARY 

1.  The  usual  number  of  chromosomes  found  in  the  sperma- 
togonia  of  Aneides  lugubris  is  twenty-eight. 

2.  The  V-figures  at  the  beginning  of  polarization  number 
twenty-six  to  thirty,  and  Ys  at  a  slightly  later  stage  twenty-eight. 

3.  The  number  of  polarized  loops  and  of  tetrads  formed  from 
the  loops  is  fourteen. 

4.  Each  tetrad  is  the  result  of  a  parasynaptic  union  of  fine 
threads. 

Transmitted  May  3,  1913. 


LITERATURE  CITED 

ElSEN,   G. 

1900.  The  spermatogenesis  of  Batrachoseps.    Journ.  Morph.,  17,  1-117, 

pis.  1-14,  12  figs,  in  text. 
FICK,  E. 

1908.     Zur   Konjugation    der   Chromosomen.      Arch.    f.   Zellforsch.,    1, 

604-611. 
FLEMMING,  W. 

1887.     Neue  Beitrage  zur  Kenntnis  der  Zelle.     Arch.  f.  mikr.  Anat., 
29,  389-463,  pis.  23-26. 

GOLDSCHMIDT,  B. 

1906.     Eeview    of   work    of    the    Schreiners.      Zool.    Centralblatt,    13 

611-612. 
1908.     1st  eine  parallele  Chromosomen-konjugation  bewiesen?     Arch. 

f.  Zellforsch,  1,  620-622. 
JANSSENS,  F.  A. 

1901.  La  spermatogenese  chez  les  tritons.    La  Cellule,  19,  7-116,  3  pis. 
1905.     Evolution  des  auxocytes  males  du  Batrachoseps  attenuatus.  Ibid., 

22,  377-425,  7  pis. 


1914]        Snook-Long:  Parasynapsis  in  Aneides  lugubris          525 

JANSSEXS,  F.  A.  ET  DUMEZ,  E. 

1903.     L' element   nucleinien  pendant   les   eineses    de   maturation   des 
spermatocytes    chez    Batrachoseps    attenuatus  ~el  ~Pleihodon 
cinereus.    La  Cellule,  20,  419-461,  5  pis. 
JANSSENS,  F.  A.  ET  WILLEMS. 

1908.  Spermatogenese  dans  les  batraciens,  IV.  Le  spermatogenese 
dans  1'  Alytes  obstetricus.  La  Cellule,  25,  151-173,  2  pis. 

KINGSBURY,  B.  F. 

1902.  The  spermatogenesis  of  Desmognathus  fusca.    Amer.  Journ.  Anat., 

1,  99-135,  pis.  1-4,  1  fig.  in  text. 

MCGREGOR,  J.  H. 

1899.  The  spermatogenesis  of  Amphiuma.  Journ  Morph.,  15  (Supple- 
ment), 57-104,  pis.  4-5. 

MEVES,  F. 

1896.     Ueber   die   Entwicklung   der   mannlichen   Geschlechtzellen   von 

Salamandra  maculosa.    Arch.  f.  mikr.  Anat.,  48,  1-83,  pis.  1-5. 

1908.     Es  gibt  keine  parallele  Konjugation  der  Chromosomen.     Arch. 

f.  Zellforsch.,  1,  612-619,  1  fig.  in  text. 

1911.     Chromosomenlangen    bei    Salamandra,    nebst    Bemerkung    zur 
Individualitatstheorie    der    Chromosomen.      Arch.    f.    mikr. 
Anat.,  77,  Abt.  2,  273-300,  pis.  11-12. 
MONTGOMERY,  T.  H. 

1903.  The  heterotypic  maturation  mitosis  in  Amphibia  and  its  gen- 

eral significance.     Biol.  Bull.,  4,  259-269,  8  figs,  in  text. 

1904.  Some    observations    and    considerations    upon    the    maturation 

phenomena  of  the  germ  cells.     Ibid.,  6,  137-158,  30  figs. 

1911.  The    spermatogenesis    of    an    hemipteron,    Euchistus.      Journ. 

Morph.,  22,  731-798,  5  pis. 
BITTER,  W.  E.,  and  MILLER,  L. 

1899.     A  contribution  to  the  life-history  of  Autodax  lugubris  Hallow, 
a  California  salamander.     Amer.  Nat.,  33,  691-704,  7  figs,  in 
text. 
SCHREINER,  A.  und  K.  E. 

1906  a.  Neue  Studien  iiber  die  Chromatinreif  ung  der  Geschlechtszellen ; 
I.  Die  Eeifung  der  mannlichen  Geschlechtszellen  von  Tomop- 
teris  onisciformis.  Arch.  Biol.,  22,  1-69,  pis.  1-3,  2  figs,  in 
text. 

1906  b.     II.  Eeifung  der  mannlichen  Geschlechtszellen  von  Salamandra 
maculosa  (Laur.),  Spinax  niger  (Bonap.)  und  Myxine  glutinosa 
(L.).     Ibid.,  22,  419-492,  pis.  23-26,  1  fig.  in  text. 
WILSON,  E.  B. 

1912.  Studies  on  chromosomes,  VIII.    Observations  on  the  maturation- 

phenomena  in  certain  Hemiptera  and  other  forms,  with  con- 
siderations on  synapsis  and  reduction.  Journ.  Exp.  Zool.,  13, 
345-431,  9  pis. 


PLATE  '25 

All  the  figures  are  drawn  at  the  same  magnification  (x  2350)  with  a 
Spencer  2  mm.  objective,  a  Zeiss  No.  12  compensating  ocular,  and  an 
Abbe  camera  lucida.  Eeduced  magnification  on  plates,  1700  diameters. 

Fig.  1.  Spermatogonium  in  the  equatorial  plate  stage,  showing 
twenty-three  chromosomes.  Fixed  in  Zenker's  fluid  and  stained  with  iron- 
alum  haematoxylin  and  orange  G. 

Fig.  2.  Same  stage  as  above  but  with  the  usual  number  of  chromo- 
somes (twenty-eight).  Zenker's  fluid,  iron-alum  haematoxylin,  and  orange 
G. 

Fig.  3.  Spermatocyte  before  the  beginning  of  polarization.  Fixed  in 
Zenker's  solution  and  stained  with  phosphotungstic  acid  haematoxylin. 

Fig.  4.  Spermatocyte  at  the  beginning  of  polarization  showing  V- 
figures.  Zenker's  fluid  and  phosphotungstic  acid  haematoxylin. 

Fig.  5.  Spermatocyte  with  short-stemmed  Y-figures.  Phosphotungstic 
acid  after  Zenker's  fluid. 

Figs.  6  and  7  illustrate  successive  steps  in  the  pairing  of  the  threads. 
The  section  from  which  Fig.  6  was  taken  was  fixed  in  Zenker's  solution 
and  stained  with  phosphotungstic  acid  haematoxylin.  Figure  7  was  taken 
from  material  fixed  in  Bouin's  fluid  and  stained  with  iron-alum  haema- 
toxylin. 

Fig.  8.  A  lateral  view.  Loops  completed.  Zenker's  fluid  and  phos- 
photungstic acid  haematoxylin. 


[526] 


UNIV.  CALIF   PUBL.ZOOL.VOL.il 


[SNOOK  -  LONG]    PLATE   25 


HJ  S.Del 


PLATE  26 

Fig.  9,  10,  and  11.    The  loops  completed. 

Fig.  9.  Pole  view.  The  sphere  lies  above  the  nucleus.  The  twenty- 
eight  free  ends  in  the  vicinity  of  the  sphere  represent  fourteen  loops. 
Zenker's  fluid  and  phosphotungstic  acid  haematoxylin. 

Fig.  10.  Lateral  view.  Zenker's  fluid,  iron-alum  haematoxylin,  and 
orange  G. 

Fig.  11.  Section  of  spermatocyte  in  the  loop  stage.  The  loops  are 
cut  twice.  Fixed  in  Zenker's  fluid  and  stained  with  iron-alum  haematoxylin. 

Fig.  12.  Complete  cell  from  crushed  preparation  showing  the  begin- 
ning of  the  split.  Flemming's  fluid  and  iron-alum  haematoxylin. 

Fig.  13.  "  Strepsinema. "  Only  a  small  portion  of  the  cell  included 
in  the  section.  Gilson  's  fluid,  iron-alum  haematoxylin,  and  orange  G. 

Fig.  14.  Prophase  to  first  maturation  division.  Complete  cell  from 
crushed  preparation — somewhat  flattened.  Flemming's  fluid  and  iron- 
alum  haematoxylin. 


[528] 


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[SNOOK  -  LONG]    PLATE   £6 
,        V 


~ 


H.  J.S.Del. 


UNIVERSITY  OF  CALIFORNIA  PUBLICATIONS— (Continued) 

5.  On  the  Skeletal  Morphology  of  Gonyaulax  catenata   (Levander),  by 

Charles  Atwood  Kofoid.    Pp.  287-294,  plate  18. 

6.  Diuoiiagellata  of  the  San  Diego  Region,  V.  On  Spiraulax,  a  New  Genus 

of  the  Peridinida,  by  Charles  Atwood  Kofoid.    Pp.  295-300,  plate  19. 

Nos.  4,  5,  and  6  in  one  cover.    September,  1911 „    1.50 

7.  Notes  on  Some  Cephalopods  in  the  Collection  of  the  University  of  Cali- 

fornia, by  S,  S.  Berry.    Pp.  301-310,  plates  20-21.    September,  1911.      .10 

8.  On  a  Self-Closing  Plankton  Net  for  Horizontal  Towing,  by  Charles 

Atwood  Kofoid.    Pp.  311-348,  plates  22-25. 

9.  On  an  Improved  Form  of  Self-closing  Water-bucket  for  Plankton  In- 

vestigations, by  Charles  Atwood  Kofoid.    Pp.  349-352. 

Nos.  8  and  9  in  one  cover.    November,  1911 _ .40 

Index,  pp.  353-357. 

Vol.  9.  1.  The  Honied  Lizards  of  California  and  Nevada  of  the  Genera  Phryno- 
soma  and  Anota,  by  Harold  C.  Bryant.  Pp.  1-84,  plates  1-9.  Decem- 
ber, 1911  .70 

2.  On  a  Lymphoid  Structure  Lying  Over  the  Myelencephalon  of  Lepisos- 

tens,  by  Asa  C.  Chandler.    Pp.  85-104,  plates  10-12.    December,  1911.      .25 

3.  Studies  on  Early  Stages  of  Development  in  Rats  and  Mice,  No.  3,  by 

E.  L.  Mark  and  J.  A.  Long.  The  Living  Eggs  of  Rats  and  Mice  with 
a  Description  of  Apparatus  for  Obtaining  and  Observing  Them  (Pre- 
liminary paper),  by  J.  A.  Long.  Pp.  105-136,  plates  13-17.  February, 
1912 -  .30 

4.  The  Marine  Biological  Station  of  San  Diego,  Its  History,  Present  Con- 

ditions, Achievements,  and  Aims,  by  Wm.  E.  Bitter,  Pp.  137-248, 

plates  18-24,  and  2  maps.    March,  1912  _ „    1.00 

6.  Oxygen  and  Polarity  in  Tubularia,  by  Harry  Beal  Torrey.    Pp.  249- 

251.     May,  1912  -      .03 

6.  The  Occurrence  and  Vertical  Distribution  of  the  Copepoda  of  the  San 

Diego  Region,  with  particular  reference  to  Nineteen  Species,  by  Cal- 
vin O.  Esterly.  Pp.  253-340,  7  text-figures.  July,  1912 1.00 

7.  Observations  on  the  Suckling  Period  in  tte  Guinea-Pig,  by  J.  Marion 

Read.    Pp.  341-351.    September,  1912  10 

8.  Haeckel's  Sethocephalus  eucecryphalus  (Radiolaria),  a  Marine  Ciliate, 

by  Charles  Atwood  Kofoid.    Pp.  353-357.    September,  1912  .08 

Index,  pp.  359-365. 

Vol.  10.    (Contributions  from  the  Museum  of  Vertebrate  Zoology.) 

1.  Report  on  a  Collection  of  Birds  and  Mammals  from  Vancouver  Island, 

by  Harry  S.  Swarth.    Pp.  1-124,  plates  1-4.    February,  1912 1.00 

2.  A  New  Cony  from  the  Vicinity  of  Mount  Whitney,  by  Joseph  Grinnell. 

Pp.  125-129.     January,  1912 05 

3.  The  Mole  of  Southern  California,  by  J.  Grinnell  and  H.  S,  Swarth. 

Pp.  131-136,  2  text-figures. 

4.  Myotis  orinomus  Elliott,  a  Bat  New  to  California,  by  J.  Grinnell  and 

H.  S.  Swarth.    Pp.  137-142,  2  text-figures. 

Nos.  3  and  4  in  one  cover.    April,  1912  12 

5.  The  Bighorn  of  the  Sierra  Nevada,  by  Joseph  Grinnell.    Pp.  143-153, 

4  text-figures.    May,  1912  10 

6.  A  New  Perognathus  from  the  San  Joaquin  Valley,   California,   by 

Walter  P.  Taylor.    Pp.  155-166,  1  text-figure. 

7.  The  Beaver  of  West  Central  California,  by  Walter  P.  Taylor.     Pp. 

167-169. 

Nos.  6  and  7  in  one  cover.    May,  1912 15 

8.  The  Two  Pocket  Gophers  of  the  Region  Contiguous  to  the  Lower  Colo- 

rado River,  in  California  and  Arizona,  by  Joseph  Grinnell.  Pp.  171- 
178.  June,  1912  15 

9.  The  Species  of  the  Mammalian  Genus  Sorex  of  West-Central  Cali- 

fornia, with  a  note  on  the  Vertebrate  Palustrine  Faunas  of  the 

Region,  by  Joseph  Grinnell.  Pp.  179-195,  figs.  1-6.    March,  1913 15 

10.  An  Account  of  the  Birds  and  Mammals  of  the  San  Jacinto  Area  of 
Southern  California,  with  Remarks  Upon  the  Behavior  of  Geographic 
Races  on  the  Margins  of  Their  Habitats,  by  J.  Grinnell  and  H.  S. 

Swarth.    Pp.  197-406,  pis.  6-10.    October,  1913 2.00 

Index,  pp.  407-417. 


UNIVERSITY  OF  CALIFORNIA  PUBLICATIONS— (Continued) 

Vol.  11.    1.  Birds  in  Relation  to  a  Grasshopper  Outbreak  in  California,  by  Harold 

C.  Bryant.    Pp.  1-20.    November,  1912  20 

2.  On  the  Structure  and  Relationships  of  Dinosphaera  palustris  (Lemm.), 

by  Charles  Atwood  Kofoid  and  Josephine  Rigdea  Michener.    Pp.  21- 

28.     December,  1912  10 

3.  A   Study   of   Epithelioma   Contagiosum    of   the   Common   Fowl,   by 

Clifford  D.  Sweet.    Pp.  29-51.    January,  1913  .25 

4.  The  Control  of  Pigment  Formation  in  Amphibian  Larvae,  by  Myrtl* 

E.  Johnson.    Pp.  63-88,  plate  1.    March,  1913  .86 

5.  Sagitta   calif  arnica,   n.  sp.,    from   the   San   Diego    Region,   including 

Remarks  on  Its  Variation  and  Distribution,  by  Ellis  L.  Michael. 

Pp.  89-126,  plate  2.    June,  1913  .35 

6.  Pycnogonida  from  the  Coast  of  California,  with  Description  of  Two 

New  Species,  by  H.  V.  M.  Hall.  Pp.  127-142,  plates  3-4.  August,  1913.      .20 

7.  Observations  on  Isolated  Living  Pigment  Cells  from  the  Larvae  of 

Amphibians,  by  S.  J.  Holmes.    Pp.  143-154,  plates  5-6. 

8.  Behavior  of  Ectodermic  Epithelium  of  Tadpoles  when  Cultivated  in 

Plasma,  by  S.  J.  Holmes.    Pp.  155-172,  plates  7-8. 

Nos.  7  and  8  in  one  cover.    September,  1913 30 

9.  On  Some  California^  Schizopoda,  by  H.  J.  Hansen.    Pp.  173-180,  pi.  9. 

November,  1913  10 

10.  Fourth  1'axonomic  Report  on  the  Copepoda  of  the  San  Diego  Region, 

by  Calvin  O.  Esterly.    Pp.  181-196,  pis.  10-12.    November,  1913 _.      .16 

11.  The  Behavior  of  Leeches  with  Especial  Reference  to  Its  Modifiability, 

A.  The  General  Reactions  of  the  Leeches  Dina  microstoma  Moore  and 
Glossiphonia  stagnalis  Linnaeus;  B.  Modifiability  in  the  Behavior  of 
the  Leech  Dina  microstoma  Moore,  by  Wilson  Gee.  Pp.  197-305,  13 
text  figures.  December,  1913 —  1.00 

12.  The  Structure  of  the  Ocelli  of  Polyorchis  penicillata,  by  Etta  Viola 

Little.    Pp.  307-328,  plates  13-15.    February,  1914  20 

13.  Modifications  and  Adaptations  to  Functions  in  the  Feathers  of  Circus 

Jiudsonius,  by  Asa  C.  Chandler.  Pp.  329-376,  plates  1G-20.  March, 
1914  50 

14.  A  Determination  of  the  Economic  Status  of  the  Western  Meadowlark 

(Sturnella  neglecta)  in  California,  by  Harold  Child  Bryant.    Pp.  377- 

510,  plates  21-24,  5  text  figures.    February,  1914  1.25 

15.  Parasynaptic  Stages  in  the  Testis  of  Aneides  lugulris  (Hallowell),  by 

Harry  James  Snook  and  J.  A.  Long.    Pp.  511-528,  plates  25-26,  1  text 

fig.     April,  1914  25 

Vol.  12.    1.  A  Study  of  a  Collection  of  Geese  of  the  Branta  canadensis  Group  from 
the  San  Joaquin  Valley,  California,  by  Harry  S.  Swarth.    Pp.  1-24, 
plates  1-2,  8  text  figs.    November,  1913  SO 

2.  Nocturnal  Wanderings  of  the  California  Pocket  Gopher,  by  Harold  C. 

Bryant.    Pp.  25-29,  1  text  fig.    November,  1913  05 

3.  The  Reptiles  of  the  San  Jacinto  Area  of  Southern  California,  by  Sarah 

Rogers  Atsatt.    Pp.  31-50.    November,  1913  20 

4.  An  Account  of  the  Mammals  and  Birds  of  the  Lower  Colorado  Valley, 

with  Especial  Reference  to  the  Distributional  Problems  Presented, 

by  Joseph  Grinnell.  Pp.  51-294,  plates  3-13,  9  text  figs.  March,  1914.    2.40 

Vol.  13.    1.  The  Schizopoda  of  the  San  Diego  Region,  by  Calvin  O.  Esterly.    Pp. 

1-20,  plates  1-2.    April,  1914  15 

2.  A  Study  of  the  Occurrence  and  Manner  of  Distribution  of  the  Cteno- 

phora  of  the  San  Diego  Region,  by  Calvin  O.  Esterly.  Pp.  21-38. 
April,  1914  15 

3.  A  New  Self-Regulating  Paraffin  Bath,  by  C.  W.  Wooiworth.    Pp.  39- 

42,  2  text-figures.     April,  1914  05 


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